Let's imagine OP was trying to scam the company. The sheer gall of asking for approval on a scam would be so audacious that honestly, it wouldn't be safe to have an employee like that working on anything of value. The level of "fuck you, I don't care" that it would show would mean that the safest thing to do with an employee like that would be to fire them.
The guy didn't ask the basic question of "has OP given us any reason not to trust them?" If the answer to that was "yes", then maybe flying them out to the UK to act on the company's behalf isn't a great idea. And if that doesn't seem likely, then it's probably an employee trying to help and they should be encouraged